Christopher Columbus was an Italian by origin and like many other Europeans, he was also keen to explore Asia. For this he had devised a plan nevertheless he needed someone to finance him and provide him resources that he would need to execute his plan. In the quest of getting his mission fulfilled, Christopher Columbus presented his plans to many kings and queens but many of them refused, thinking that Columbus's plans were not feasible enough and would not have any profitable or productive outcomes.
At last Christopher Columbus found the answer to his prayers in the form of the Spanish queen Isabella. Because of the ongoing competition between European countries about power, the Spanish queen saw this plan of Columbus as an opportunity to enhance and elevate the power of Spain over other European nations. Ergo she provided Columbus with three ships and ninety sailors for him to go explore Asia and find the wealth that Spain need to entrench its superiority over the other European nations.